Centrifuge



Sept. 8, 1936. w. c. LAUGHLIN 2,054,058

CENTRIFUGE Filed April 12, 1934 3 Sheets-Sheet 1 INVENTOR BY J- I ATTORNEY Sept. 8, 1936. w. c. LAUGHLIN 2,054,058

' GENTRIFUGE Filed April 12, 1934 I 3 Sheets-Sheet 2 lNVENTOR W/umM CT [Am/mm.

BY @Mm m;

ATTORNEY P 1936- w. c. LAUGHLIN 2,054,058

CENTRIFUGE Filed April 12, 1954 3 Sheets-Sheet 3 INVENTOR lr/uui/w C [warm/1v.

OJ: f b -7 ATTORNEY Patented Sept. 8, 1936 UNITED STATES PATENT OFFICE CENTRIFUGE Application April 12, 1934, Serial No. 720,189

4 Claims. (01. 233-7) This invention relates to a novel method of and apparatus for separating a liquid mixture into fractions of different specific gravities by centrifugal action.

More particularly, the invention relates to improvements in centrifuges constructed to enable withdrawal of a relatively light fraction of it treated liquid from the centrifuge bowl at one level, at a point inwardly of the side walls of the bowl andwithdrawal of a relatively heavy or dense fraction from the bowl at another point.

A more specific feature resides in the provision of an improved centrifuge adapted to cleanly separate liquids containing finely divided solids into a heavy liquid containing most of the solids and a light liquid substantially free of solids. Preferably, provision is made for discharging the solids from the centrifuge along with the heavy fraction, but in one form disclosed herein there is provision for separately discharging the solids.

A further feature resides in providing means for enabling ready adjustment of the centrifuge for different densities of one or both of the fractions to be separated, thus providing flexibility for handling liquids of varying character.

Still another feature resides in the provision of means for preventing solid particles in the liquid from collecting in the bottom of the bowl and for aiding in carrying them to the desired point of discharge.

Another feature of the invention resides in providing an improved centrifuge of the character indicated, which shall be comparatively simple and inexpensive to manufacture, efllcient in operation and durable in service.

Other features, objects and advantages of the invention will be in part apparent and in part pointed out in connection with the following detailed description of one form of centrifuge in accordance with my invention, reference being ha to the accompanying drawings wherein.

Fig. 1 is a central, vertical section, partly in elevation and partly broken away, of a preferred form of centrifuge in accordance with the invention;

Figs. 2, 3 and 4 are sections taken on the lines 2--2, 3-3 and 4-4, respectively, of Fig. 1, looking in the directions of the respective arrows;

Fig. 5 is a central, vertical section of a modifled form of 'a centrifuge, also in accordance with the invention; and

Fig. 6 is a section taken on-the line 6'-6 of .Fig. .5, looking in the direction of the arrows.

As shown in the drawings, the centrifuge may comprise a suitable base 5 adapted to stand on the floor or other support, and a housing 6 secured to the base. The housing 5 may be provided with a cover or top 1 arranged to support an electric motor and driving connections for rotating the revolving parts of the centrifuge. 5 For example, a gear housing 8 may be bolted or otherwise secured to convenient flanges formed on the cover 1, and a motor 9 may be supported on the gear housing through a bracket l0. Bearings II and I2 may be received in the cover I 10 andtop wall of housing 8, respectively, for mounting a shaft l3 connected to: the motor'shaft M in any suitable manner. Ifdesired, any suitable gearing I 3' may be provided for operating an oil pump (not shown) for forcing lubricant into the 15 gear housing through pipes l3".

Keyed to the shaft ii there are provided gears l4 and ii for driving gears I6 and I1, respectively keyed to main shaft l8 of the centrifuge and to a sleeve l9 journalled on this shaft. The 2 upper end of shaft It! may be journalled in a bearing 2|, while the sleeve l9 may be journalled througn a collar 22 in a bearing 23 carried by the top I. The shaft I8 and sleeve l9 extend through the top I of housing 6. A suitable bush- 25 ing 24, for receiving sleeve l9, may be fltted in the top I.

Within the housing 6 there is provided a bowl 25 which may be formed of a cylindrical member 26 and end plates 21, 28 secured thereto through 30 angle irons 29. The top end plate 21 may be attached to the lower end of sleeve IQ, for instance by welding. The bottom end plate 28 may be secured to a flanged member 30 keyed to a stub shaft 3i which is mounted in bearings 33, 34 carried by a suitable housing 32. The bearing 34 serves as a thrust. bearing. Upstanding flanges 35 may be provided on the'top of housing 32 for cooperating with flanged member 30 in order to prevent any liquid, which may 40 fall to the bottom of housing 6, from reaching bearings 32 and 34. A suitable outlet 31 is shown formed in the bottom of housing 6 to permit such liquid to drain therefrom, and a hand hole may also be formed in the bottom of housing 6 ,5 for reaching plugs 39 in the bottom of the bowl, when it is desired to drain liquid from the latter.

The shaft 18 is preferably formed hollow for receiving a pipe 40 which extends from above the upper end to the shaft to near the bottom of the bowl and serves as the feed inlet for liquid to be acted upon by the centrifuge. The pipe 40 may be threaded as at 42 into a suitable cap 4| on the gear housing 8.

Secured to the shaft it within the bowl 2! there is provided an impeller or screw comprising blades 43 and 44, preferably of generally helical or spiral shape. A fiat plate 43' is preferably secured across the bottom or formed as part of the blade 43, and a similar plate 44' is preferably provided at the top of blade 44. The blades are advantageously of such diameter as to extend close to the walls of the bowl, while the plates 43' and 44' may be of somewhat smaller diameter. The. plates 43' and 44' are preferably spaced a substantial distance from the end walls of the bowl, for instance as shown, and provision is made for agitating and keeping in motion the relatively heavy liquid adjacent the walls of the bowl.' For this purpose, there are advantageously provided arms or fins 45, welded or otherwise attached to plates 43' and 44', and. extending so that their upper and lower edges lie close to the end walls of the bowl. Any convenient number of fins may be employed. However, good results are achieved when four fins are employed at the top and four at the bottom, equally spaced around the circumference of the blades. The outer edges of the fins preferably lie close to the side walls of the-bowl, while the finsmay extend inwardlytoward the axis of the centrifuge to about a third or so of the radius, though they may be of greater or less extent.

It may be advantageous in certain cases to construct the fins so that they extend at angles to radii, or in other words so that their outer ends lead or lag with respect to their inner ends and with relation to the direction of rotation of the blades. For instance, the lower fins may extend with their outer ends lagging in order to assist the forces tending to throw solids toward the side walls of the bowl, while the upper blades, in the form illustrated, may extend with their outer ends leading in order to urge the material, which is to be discharged through outlet ports 54, toward these outlets.

Where desired, suitable perforations 45 may be provided adjacent the perimeters of the blades, and such perforations are advantageous in the upper blade 44, which is above the outlets for the light fraction, hereafter described. It is also desirable to thicken the edges of the blades, especially the upper blade, for instances as shown at 41, by means of strips folded to lie over and under the edges of the blades and secured thereto. The blades are thus strengthened and the bowl, so that the distance each tube projects into uniform elevation of the heavier fraction is promoted.

Between the blade 43 and the blade 44 a space is provided into which extend a series of tubes 50. Four are shown, although any satisfactory number may be employed. Each of these tubes is shown threaded into a fiange 5|, carried by the justment.

It will be appreciated that if the centrifuge be operated at less than capacity, the speed of rotation of the bowl may be employed, within ascertainable limits, to vary the density characteristic of the liquid discharged through the tubes 50. For instance, by reducing the speed somewhat, more liquid will tend to fiow out through tubes 50, due to reduction of the force tending to throw the liquid toward the side walls of the bowl.

Oriflces 54, connected with radial passages 55, are formed at the top of the bowl and serve as outlets for the liquids of relatively heavy density. Advantageously, the orifices 54 are positioned inwardly of the inner ends of blades 45. The orifices 54 may be open at the top for venting air, but the liquid will still pass through passages 55 due to the rapid rotation of the bowl.

The housing 6 may be provided with an integral, internal flange 56 forming an annular compartment 51 for receiving the heavy fraction as discharged from the bowl, and with a similar flange 58 forming a compartment 59 for receiving the light fraction as discharged. Ports 60 teeth than gear ii. For instance, if the shaft "and the blades thereon are to rotate 'at 900 R. P. M. and the bowl 25 is to rotate at 890 R. P. M., the gears may be'readily designed to effect this speed differential. Such a speed differential aids in producing a uniform distribution of the liquids, in eliminating deposits of solids, and in carrying solids toward the heavy liquid discharge outlets in the bowl. However, the invention is not limited to any particular speed differential. v

The operation of the centrifuge will be understood from the foregoing, but may be summarized here. The centrifuge is first started and then liquid to be treated is continuously admitted to the top of pipe 40 and flows downwardly therethrough, entering the'bowl 25 near the bottom thereof. As the liquid is centrifuged .it stratifies into a relatively dense or heavy layer adjacent the side walls of the bowl, and a relatively thin or light layer nearer the axis, and as the level -ofthe liquids rises in the bowl an equilibrium is soon reached, whereupon the light liquid is discharged through tubes 50 into compartment 59 and the heavy liquid is discharged through orifices 54 into compartment 51. It will be seen that the heavy fraction is permitted to flow past the edges of blade 44 and onto the top of plate 44' between the fins 45, thus reaching the orifices 54. The rate of feed may be readily controlled to maintain the quantity of liquid in the bowl constant, once the machine is operating at a predetermined speed or a particular capacity.

While the present invention in its broader aspects is not confined to use with any particular materials to be treated, it has been developed and is especially useful in connection with doctor sludges produced in sweetening operations in oil refineries. Such doctor sludges commonly contain lead sulfide, caustic solution, and naphtha, in the form of an emulsion, and it becomes desirable to separate the naphtha from the other materials. When such a doctor sludge, containing the lead sulfide particles in suspension, is treated as mentioned, the relatively lightnaphtha is readily separated, as much as 99% of it being recovered, while by far the major part of the lead sulfide is carried along and discharged with the caustic solution. By adjusting the tubes 58 to reduce the proportion of the naphtha cut, a naphtha fraction substantially free of lead sulfide may be produced. .Additional recovery of naphtha from the heavier liquid may then be achieved by returning this liquid to the centrifuge along with additional doctor sludge, or by treating it in a separate centrifuge, or otherwise.

Whilethe form of centrifuge shown in Figs. 1-4 has especial advantages for purposes indicated, certain of these advantages, and others, may be achieved through modified forms of construction, one of which is illustrated in Figs. 5 and 6 to which reference will. now be made.

The form of'machine shown somewhat diagrammatically in these latter figures may comprise aconical bowl I0 journalled on a horizontal shaft H through sleeves 12 and 18 at the ends of the bowl. The shaft '|l may be supported in any convenient external bearings, and the shaft and sleeve 12 may be rotated from a suitable source of power (not shown). Within the bowl 10 there may advantageously be provided a hollow conical member H carrying a-spiral blade I! on its outer side. The member 14 may be supported on the shaft 1| through sleeves 18 and 11 secured thereto.

Liquid to be centrifuged may conveniently be admitted to the bowl, preferably to the small end thereof, through a pipe 18, at a rate controlled by valve 19, this pipe being suitably connected with the hollow end 88 of shaft 1i. A convenient number of tubes 8| extend radially from the inner end' of the hollow portion 88 to the space between the bowl and member II, for conducting the liquid into the bowl.

Surrounding the outlet or large end of thebowl 10 there is provided a housing 82 which receives the relatively heavy liquid fraction discharged from the bowl through ports 83 formed in the end wall 84 thereof. The distance of these ports from the perimeter of the bowl, at a given speed of rotation, will determine the density of the liquid withdrawn through the ports, and .suitable, adjustable closure plates 85 may be provided to control the density and/or quantity of liquid discharged. For instance, the plates 85 may be mounted on set-screws which can be tightened down when the plates have beeen moved to the proper positions. However, any other convenient device -may be used for this purpose.

Similar ports 86 and closure plates 81 may be provided, spaced farther from the perimeter of the bowl than ports 83, for withdrawing lighter or less dense liquid from the bowl, and the liquid thus withdrawn may be conducted by means of a circular baffle 88 into a housing 89. The balile '88 may advantageously extend inwardly of the end wall of the 'bowl and be provided with a gen erally radial flange '90 of suflicient extent to aid in producing a clean separation of the heavy and light fractions. In other words, the baflie and flange construction aids in preventing the lighter fraction from reaching the ports 83. Openings 92 may be provided in the large end of the member II, for permitting this member to receive a portion of the liquid in the centrifuge, and thus enabling the stratification of the liquid fractions to take place in a relatively large volume of liquid, while at the same time the spacev between the cone I4 and bowl 18 may be restricted, to facilitate the desiredoperation of the blades 15, as will be hereafter described.

Surrounding the small end of the bowl I8 is a amount of liquid carried out of the small and of I the bowl may be reduced.

Suitable piping 95, 98, 91 may be provided for drawing off the several fractions from housings 82, 89 and 93 and passing them to storage reservoirs 98, 99 and I88, respectively.

In operation of this form of centrifuge, it will be understood from the foregoing that liquid to be treated is fed in through pipe 18, the bowl l8 and member 14 being revolved through suitable connections with shaft and sleeve 12. A speed differential may be employed, where desired, as described in connection with Figs. 1-4. As the liquid level builds up to the desired constant, the heavy liquid will be thrown out from the axis'uof the bowl and will discharge continuously at the desired Irate from openings 83, while the lighter fraction will discharge continuously through ports 88. The blade 15 will sweep solid particles, which tend to settle in the heavy liquid, toward the small end of the bowl and there discharge them.

Through the present construction there is thus provided a particularly simple and effective centrifuge for producing a separation of liquids into fractions of different specific gravities, and espeeconomical in use.

It will be appreciated that in addition to many of the advantages of. the vertical type centrifuge, which is particularly eflicient in operation, provision is made in the horizontal type for a separate removal of solid particles, thus eliminating in certain cases the need for a separate settling chamber, in the event that it is desirable to remove the solid particles from the. heavy liquid' fraction.

The terms and expressions which have been employed are used as terms of description and not of limitation, andthere is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are'possible within the scope of the invention claimed.

What is claimed is:

1. In a centrifuge of the character described, adapted to separate a mixture of oily liquids and solids into a heavy liquid containing substantially all the solids and a light liquid, in combination, a bowl rotatable on a vertical axis and having a solid side wall and end walls, a screw within said bowl, shafting secured to opposite end walls of the bowl, a driving element co-axial with said shafting and secured to said screw, a fixed, central feed pipe opening into said bowl adjacent one end thereof, a plate carried by said driving element at the end of the screw adjacent the opposite end of the bowl from the feed end, said plate being constructed and arranged to form a narrow passage between its edges and the side wall of the bowl, openings in the-end wall of the bowl adjacent said plate for discharging heavy liquid containing solids from said passage, tubes carried by said bowl and extending into the same between the ends thereof for discharging light liquid, and fins carried by said screw adjacent the feed end of the bowl and the side wall thereof for imparting rotary motionto the liquid.

2. In a centrifuge of the character described, adapted to separate a mixture of liquids and solids into a heavy liquid and a light liquid, one of which contains most of the solids, a bowl hav' ing solid side and end walls, a screw within said bowl, shafting secured to opposite end walls of the bowl, a driving element co-axial with said shafting and secured to said screw, a fixed central stationary feed pipe opening into said bowl, two plates, one at each end of the screw, secured to said driving element, the plate opposite the feed end being constructed and arranged to form a narrow passage between its edges and the side wall of the bowl for discharging heavy liquid containing solids through said passage, tubes carried by said bowl and extending into the same between the ends thereof for discharging light liquids, and arms carried by said plates adjacent the side and end walls of the bowl for imparting rotary motion to the liquid and for assisting in removing solids which tend to settle and adhere to the walls of the bowl.

3. In a centrifuge as claimed in claim 2, the

construction comprising a screw having plates extending outwardly from the driving element to adjacent the side wall of the bowl and the spaces between said plates being otherwise substantially unobstructed.

4. In a centrifuge as claimed in claim 2, wherein certain of said arms are mounted on the plate at the discharge end of the bowl between the plate and the end wall of the bowl, for imparting rotary motion to the material delivered from the screw between the edge of the plate and the side wall of the bowl.

WILLIAM C. LAUGHLIN. 

